# In-group neural alignment serves as a biomarker of social identity

Raw fMRI data for:
Yohay Zvi (1), Nitai Kerem (1), Eldad Aviv (2), Yaara Yeshurun (1, 2).
In-group neural alignment serves as a biomarker of social identity.
PNAS (accepted; DOI to be added).

(1) Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
(2) School of Psychological Sciences, Tel Aviv University, Tel Aviv, Israel

Yaara Yeshurun Lab, Tel Aviv University.
Contact: Yohay Zvi (yohayzvi@gmail.com), Yaara Yeshurun (yaara.yeshurun@gmail.com)

## Participants
42 healthy, right-handed native Hebrew speakers (ages 21-33):
- Religious (N = 21, 13 female): sub-rel01 ... sub-rel21
- Secular   (N = 21, 14 female): sub-sec01 ... sub-sec21
Group membership is listed in participants.tsv. Participants were assigned to
groups by a preliminary questionnaire; religious participants were recruited from
a less conservative sector to ensure familiarity with the stimuli without offense.
The study was approved by Tel Aviv University's Ethics Committee and by the
Helsinki Institutional Committee of the Sheba Tel-Hashomer Medical Center, and
all participants gave written informed consent.

## Task: free-viewing video task
A single free-viewing video task. Participants passively watched three short
Hebrew social media and TV news videos, one per run, with no task during viewing.
Because this is naturalistic viewing, there are no events.tsv files.
- task-neutral: weather report (2:07)
- task-kosher:  video presented by a religious spokesman describing the risks of
                non-institutional Kosher certification (2:23)
- task-chametz: news report on hospitals banning Chametz during Passover (2:33)
Each video was preceded by 8 s and followed by 10 s of grey screen, so the video
starts 8 s (8 volumes) after the first volume of each run. The neutral video was
always shown first; the order of the Kosher and Chametz videos varied across
participants.

After each video, participants rated agreement, interest and emotional engagement
on a visual analogue scale (0-100) inside the scanner. These ratings, the
post-scan questionnaires and the stimuli are available on OSF (see below), not in
this dataset.

### Run length
The number of volumes per run varies across participants (137-220). Recording was
stopped at different points relative to the in-scanner rating questions: for some
participants before the questions, for others during or after them. Volumes after
the end of the 10 s post-video grey screen may therefore include the rating period
and should not be treated as stimulus-driven.
sub-rel18 task-neutral is shorter (137 volumes) due to a technical problem with
the scanner; 128 TRs of this video were used in the analyses reported in the paper.

## MRI acquisition
Siemens Prisma 3T, 64-channel head-neck coil.
- T1w: MPRAGE, TR = 2400 ms, TE = 2.78 ms, TI = 1000 ms, flip angle 8 deg,
  bandwidth 200 Hz/px, GRAPPA 2, 0.9 mm isotropic.
- BOLD: multiband gradient-echo EPI (CMRR), multiband factor 6, TR = 1000 ms,
  TE = 30 ms, flip angle 60 deg, 2 mm isotropic, 72 slices.
Acquisition parameters are taken from the DICOM headers and are listed in full in
each image's JSON sidecar. DICOMs were converted to NIfTI with dcm2niix
(v1.0.20190902). T1w images were defaced with quickshear (v1.2.0), using each
participant's brain mask.

## Related resources
Stimuli, behavioral data and analysis code (OSF):
https://osf.io/a9xqj/
GitHub repository: https://github.com/YohayZvi/religion-neuro-sync